package mark.tom.fiter.http.ssl;

import java.util.regex.Pattern;

class InetAddressUtils {

    private static final String IPV4_BASIC_PATTERN_STRING = "(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.){3}"
            + "([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])";

    private static final Pattern IPV4_PATTERN = Pattern.compile("^"
            + IPV4_BASIC_PATTERN_STRING + "$");

    private static final Pattern IPV4_MAPPED_IPV6_PATTERN = Pattern
            .compile("^::[fF]{4}:" + IPV4_BASIC_PATTERN_STRING + "$");

    private static final Pattern IPV6_STD_PATTERN = Pattern
            .compile("^[0-9a-fA-F]{1,4}(:[0-9a-fA-F]{1,4}){7}$");

    private static final Pattern IPV6_HEX_COMPRESSED_PATTERN = Pattern
            .compile("^(([0-9A-Fa-f]{1,4}(:[0-9A-Fa-f]{1,4}){0,5})?)" + "::"
                    + "(([0-9A-Fa-f]{1,4}(:[0-9A-Fa-f]{1,4}){0,5})?)$");

    private static final char COLON_CHAR = ':';

    private static final int MAX_COLON_COUNT = 7;

    static boolean isIPv4Address(final String input) {
        return IPV4_PATTERN.matcher(input).matches();
    }

    public static boolean isIPv4MappedIPv64Address(final String input) {
        return IPV4_MAPPED_IPV6_PATTERN.matcher(input).matches();
    }

    private static boolean isIPv6StdAddress(final String input) {
        return IPV6_STD_PATTERN.matcher(input).matches();
    }

    private static boolean isIPv6HexCompressedAddress(final String input) {
        int colonCount = 0;
        for (int i = 0; i < input.length(); i++) {
            if (input.charAt(i) == COLON_CHAR) {
                colonCount++;
            }
        }
        return colonCount <= MAX_COLON_COUNT
                && IPV6_HEX_COMPRESSED_PATTERN.matcher(input).matches();
    }

    static boolean isIPv6Address(final String input) {
        return isIPv6StdAddress(input) || isIPv6HexCompressedAddress(input);
    }

}